optimize ScHTMLExport::WriteTables() with large columns

Again, unless given a hint, mdds always starts a search from the beginning
of the container, so iterating over a column becomes quadratic.
Shows when selecting (the title of) a large column with different value types,
e.g. in tdf#120558, which triggers setting the selection from
VclQt5Clipboard::setContents(), which calls this.

Change-Id: Ida009c5ddf18ccdc8dff88c15530cc7e33ce80e7
Reviewed-on: https://gerrit.libreoffice.org/72366
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/sc/source/core/data/column.cxx b/sc/source/core/data/column.cxx
index 70ee70b8e1f4..548e6403cc8b 100644
--- a/sc/source/core/data/column.cxx
+++ b/sc/source/core/data/column.cxx
@@ -726,6 +726,16 @@ ScRefCellValue ScColumn::GetCellValue( SCROW nRow ) const
     return GetCellValue(aPos.first, aPos.second);
 }
 
+ScRefCellValue ScColumn::GetCellValue( sc::ColumnBlockPosition& rBlockPos, SCROW nRow )
+{
+    std::pair<sc::CellStoreType::iterator,size_t> aPos = maCells.position(rBlockPos.miCellPos, nRow);
+    if (aPos.first == maCells.end())
+        return ScRefCellValue();
+
+    rBlockPos.miCellPos = aPos.first; // Store this for next call.
+    return GetCellValue(aPos.first, aPos.second);
+}
+
 ScRefCellValue ScColumn::GetCellValue( sc::ColumnBlockConstPosition& rBlockPos, SCROW nRow ) const
 {
     std::pair<sc::CellStoreType::const_iterator,size_t> aPos = maCells.position(rBlockPos.miCellPos, nRow);